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2017 Q50 3.0t - Experiencing Transmission Shudder and Harsh Downshifts

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Mike T. · rep 0 · May 24, 2:52 PM · 1 replies · solved · Question

Vehicle: 2017 Infiniti Q50 3.0t Premium

Hey everyone,

I've got a 2017 Infiniti Q50 3.0t Premium with about 75,000 miles, and lately, I've noticed some concerning behavior from the transmission. When accelerating, especially under moderate throttle, there's a distinct shudder or hesitation, almost like it's struggling to find the right gear. It's not constant, but it's happening more frequently.

Even more annoying are the harsh downshifts, particularly when coming to a stop or slowing down. It feels like a noticeable jolt, which definitely wasn't there when I first got the car. I'm worried this could be a sign of a bigger problem.

Has anyone else with a 2016-2020 Q50 experienced similar transmission issues? What was the cause, and what did your mechanic recommend? I'm trying to figure out if this is a common reliability concern or something specific to my vehicle. Any advice on what to check or ask about when I take it to the shop would be greatly appreciated!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 24, 2:52 PM

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ClearTheCode admin answer:

It sounds like you're experiencing some common symptoms that can arise with the 7-speed automatic transmission in the Infiniti Q50, especially as it accumulates mileage. This type of shuddering and harsh shifting can be attributed to several factors:

  1. Transmission Fluid Degradation: Over time and mileage, transmission fluid breaks down and loses its lubricating and cooling properties. This can lead to increased friction, poor hydraulic pressure, and erratic shifting. While Infiniti often states 'lifetime' fluid, it's generally recommended for inspection and potential replacement around the 60,000-90,000 mile mark, especially for vehicles driven in demanding conditions.
  2. Valve Body Issues: The valve body is a complex component within the transmission that controls fluid flow to engage different gears. Malfunctions or wear in the solenoids or valves within the valve body can lead to inconsistent pressure, causing harsh shifts, delays, or shuddering. This has been a known area of concern for some Nissan/Infiniti transmissions.
  3. Transmission Control Module (TCM) Software: Sometimes, the issue isn't mechanical but electronic. Outdated or corrupted software in the TCM can cause incorrect shift logic. A software update or reflash might resolve these symptoms.
  4. Torque Converter Problems: Less common, but a failing torque converter can also induce shuddering, particularly under light to moderate acceleration, as it struggles to efficiently transfer power from the engine to the transmission.

When to See a Shop:

It's highly recommended to have your vehicle inspected by a qualified Infiniti specialist or a reputable transmission shop as soon as possible. Transmission issues can escalate quickly, leading to more extensive and costly repairs if left unaddressed.

What to Expect/Ask At the Shop:

  • Diagnostic Scan: Request a thorough scan for any stored or pending diagnostic trouble codes (DTCs). Even if your check engine light isn't on, transmission-specific codes like P0700 (Transmission Control System Malfunction), P0731-P0736 (Incorrect Gear Ratio), or P17XX series codes might be present.
  • Fluid Inspection: Have them check the condition and level of the transmission fluid. They should look for signs of burning, metallic particles, or excessive sludge.
  • Test Drive: A technician should perform a test drive to confirm the symptoms and potentially pinpoint the conditions under which they occur.
  • Software Update: Inquire if there are any available Transmission Control Module (TCM) software updates or technical service bulletins (TSBs) related to your specific model year and symptoms.
  • Pressure Tests: Advanced diagnostics might include pressure tests to evaluate the valve body's performance.

Addressing this promptly can often prevent minor issues from becoming major transmission overhauls.

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